Cats Can Get Heartworms Too

April is National Heartworm Awareness Month, so here’s something you need to be aware of: Contrary to popular belief, dogs are not the only pets that can get heartworms. Cats get heartworms, too.

How do cats become infected with heartworms?

Cats become infected just like dogs do. A hungry mosquito lands on a cat and takes a blood meal by inserting its sharp mouthpart (proboscis) into the cat. The mosquito deposits immature heartworm larvae on the surface of the cat’s skin. These wiggly larvae enter through the mosquito’s feeding channel and migrate around the cat’s body. As they travel in the cat, the larvae molt and mature, eventually making their home in the blood vessels of the heart and lungs.

What happens when a cat is infected with heartworms?

In the early stages of Feline Heartworm Disease, the cat may experience respiratory problems related to the inflammation caused by the presence of the heartworm larvae in the pulmonary blood vessels. Special stem cells called pulmonary intravascular macrophages (PIMS) try to ward off the heartworms. These cells live in the tiny blood vessels in the cat’s lungs and fight to get rid of intruders, but the cat becomes ill as these cells try to kill off the larvae. The name for this stage of feline heartworm infection is Heartworm Associated Respiratory Disease (HARD), and the cat can die from it.

If both the cat and the immature worms survive, the heartworms mature and suppress PIM function. That means that a cat with adult heartworm disease may not show any illness, but when the adult worms die and PIM function is restored, the cat gets sick again and faces potential death once more.

What are the signs of feline heartworms?

The lung inflammation caused by the heartworm vs. PIMS war may result in coughing or wheezing. Cats with heartworms act like cats with asthma, so very often they are misdiagnosed. Some cats assumed to have seasonal allergies or asthma actually have HARD. Sometimes, the respiratory distress is so severe that the cat dies very suddenly. Development of a blockage in a lung vessel caused by a piece of dead worm or a blood clot may also result in the cat’s sudden demise. These cats never even make it to the emergency clinic.

Another less deadly symptom is vomiting unrelated to eating. These cats vomit at odd times and don’t respond to GI medications. Other cats develop neurological signs like lack of coordination or seizures. This occurs when the heartworm migrates in the nervous system. But the scary thing is that lots of cats don’t show any signs at all. They appear to be healthy. This is unfortunate because undiagnosed cats are also untreated cats.

What can be done for a cat with heartworms?

Unlike dogs, cats don’t have the advantage of getting rid of the adult heartworms with medical therapy. There is no FDA approved medicine to kill the adult heartworms, so cats can’t be “cured” of the infection.

Dealing with feline heartworms focuses on managing the disease. Antibiotics and steroids usually help the respiratory symptoms for a while. Since they cannot be thoroughly treated, cats with heartworms need constant monitoring for any progression of the infection. Blood work and chest radiographs are performed frequently to assess the cat’s condition. Cat owners need to keep a careful eye on the cat’s eating habits and breathing patterns and stay at the ready to provide emergency care if the cat has a sudden attack of respiratory distress or cardiac failure.

How can heartworms be prevented in the cat?

Prevention of heartworms in cats is paramount because the disease is hard to diagnose, has no specific treatment, and is deadly. Fortunately, there are many forms of monthly heartworm prevention drugs to choose from. Some are oral and others are applied topically. A big plus is the ability of heartworm medications to prevent or treat other parasites such as fleas, ear mites, and intestinal worms. It is critical to give the heartworm medication on the SAME DAY EVERY MONTH for the best results.

What cats need heartworm prevention?

ALL cats need to be on heartworm medication. Even indoor cats can become infected because mosquitoes often come indoors and bite them. If you’ve ever swatted at a mosquito in your home, you’ve witnessed how elusive these insects can be. Mosquitoes are strong survivors that will live in the driest desert and the coldest climates. That means heartworms live alongside them. So, no matter where you live, your cat needs heartworm prevention.

Talk to your veterinarian during National Heartworm Awareness Month and ask for a heartworm preventive plan for your cat. Then you can rest easy and enjoy your kitty.